Hockley Dome Mine (United Salt Mine), Hockley, Harris Co ...
Tidewater Gypsum Company drilled 9 exploration wells and sunk the shaft in 1928. It was later deepened in 1944 by the Hockley Gypsum Company which drilled 15 more wells for gypsum. The mill had a capacity of 100,000 tons of salt per year. Analytical data results: Gypsum ore mined generally exceeded 95% gypsum.